| 摘要 |
PROBLEM TO BE SOLVED: To provide an automatic train stop system to reduce an electromagnetic influence by an electric conductor positioned in the vicinity of the feedback circuit of a pick up and the resonation circuit of a ground pick up by a shield plate formed of a material having high magnetic permeability and high resistibility and be prevented from being influenced by an electromagnetic influence from the electric conductor. SOLUTION: When a given current 1 flows into the primary coil 13a of a pick up 13, a magnetic fluxϕ1 is generated at the periphery of the primary coil 13a. Since the magnetic fluxϕ1 is concentrated to a ferrite shield plate 4 having high magnetic permeability, the generation of an eddy current at the internal part of an electric conductor 15, such as iron sleepers, rails, and iron plates for reinforcing a railway, is suppressed and the generation of a magnetic flux due to the eddy current is suppressed. Since the ferrite shield plate 4 has high resistibility, even when the magnetic fluxϕis concentrated, an eddy current is not generated. As a result, the increase of relative inductance between the primary coil 13a and a secondary coil 13b is decreased and the increase of the degree of coupling therebetween is suppressed.
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